Matryoshka Dolls depicting Expedition 57 crew members Serena
Auñón-Chancellor of NASA, left, Sergey Prokopyev of Roscosmos, center,
and Alexander Gerst of ESA (European Space Agency) are seen during a
welcome ceremony at the Zhezkazgan, Kazakhstan airport on Thursday, Dec.
20, 2018. Auñón-Chancellor, Gerst, and Prokopyev are returning after
197 days in space where they served as members of the Expedition 56 and
57 crews onboard the International Space Station. Photo Credit: